1. Field of the Invention
The invention relates to methods for the alkoxylation of polyoxyalkyleneamines and more particularly relates to non-catalytic methods for alkoxylating polyoxyalkyleneamines at low temperatures in the presence of water.
2. Other Methods in the Field of the Invention
The general concept of alkoxylating polyoxyalkyleneamines is well known. However, the higher molecular weight polyoxyalkyleneamines react with higher oxides, such as propylene oxides, only with great difficulty, requiring high temperatures and long reaction times. Even under these conditions, it is quite difficult to prepare products having a tertiary amine content of greater than 90% (considered totally alkoxylated).
A number of schemes for alkoxylation have been developed. U.S. Pat. Nos. 2,902,478 and 3,865,806 both describe techniques for reacting initiators having 4 to 8 active hydrogens with alkylene oxides in the absence of added water but using trialkylamines as catalysts for the reaction. The reaction temperature for this method range from 70.degree. to 160.degree. C., preferably 80.degree. to 90.degree. C. Alkylene oxides may also be added to the reaction product of phenol, alkanolamine and formaldehyde according to U.S. Pat. No. 3,297,597. Here the process is performed in the absence of water at a temperature in the range from 30.degree. to 200.degree. C., although all of the examples therein are conducted at temperatures of 90.degree. C. or higher.
Another catalytic method is described in U.S. Pat. No. 4,075,130 where polyoxypropylene polyamines of 190 to 3,000 molecular weight may be reacted with alkylene oxides in the presence of acidic or basic catalysts at a temperature in the range of 50.degree. to 200.degree. C., apparently in the absence of water. These materials are subsequently used as defoaming agents. Aqueous ammonia is used as a catalyst for this reaction conducted at 40.degree. to 120.degree. C. according to the method of U.S. Pat. No. 4,166,172.
Non-catalytic methods include Canadian Pat. No. 914,850 which details the reaction of polyoxyalkylene polyamines with alkylene oxides at 125.degree. to 170.degree. C. in the absence of water.
It would be advantageous to have a method for alkoxylating polyoxyalkyleneamines at low temperatures, in the absence of a catalyst to give a product having greater than 90% of the amine functions as tertiary amines.